Sen. Jeff Sessions of Alabama criticized Mr. Perez, a former Montgomery County councilman and Maryland labor secretary, for his one-time service on the board of CASA de Maryland. Sen. Charles Grassley of Iowa complained that the president had nominated Mr. Perez for a cabinet post despite a congressional investigation into the Civil Rights Division and questions about whether he engineered a quid pro quo with the city of St. Paul, Minn. And Sen. David Vitter of Louisiana said he will block Mr. Perez's nomination over complaints about politically motivated enforcement of voting rights laws.

The GOP complaints about CASA are a rehash of questions from his confirmation hearing for the justice post, largely centered on the organization's objections to a 2007 immigration enforcement raid in Baltimore. To recap: Immigration and Customs Enforcement officials were told by their boss to "bring more bodies in" and "were ordered to seek additional arrests that day due to managerial pressure to produce statistics." They went to a convenience store in Fells Point and immediately started targeting Latino men while ignoring others, including a white man in a pickup truck who had been trying to hire day laborers. Caught up in the sweep was a janitor who was on his way to Johns Hopkins Hospital, where his son was being treated for cancer.

The inspector general's report that Mr. Grassley cited found significant conflict within the Civil Rights Division. But the problem dated to the Bush administration, when justice officials sought to replace career professionals with political appointees in an effort to limit enforcement of civil rights. Mr. Perez has largely resolved those problems by restoring the division's focus on vigorous enforcement of voting rights laws and housing discrimination cases.

The one quibble with Mr. Perez in the inspector general's report related to his testimony about the Justice Department's decision not to pursue a civil case against the New Black Panthers over alleged intimidation of white voters in Philadelphia. That case, which began under the Bush administration, was dropped before Mr. Perez's tenure at the department. He later testified before the U.S. Civil Rights Commission that senior officials at the Justice Department had not been involved in the decision, but last week's report found that they had participated in discussions about it, though the final decision was made by career lawyers, as Mr. Perez had said.

Senator Vitter is straining to draw a contrast between what Mr. Perez said years later about a case in which he was not involved and his department's decision to sue the state of Louisiana over its alleged failure to provide voter registration forms and services at offices providing public assistance and services for the disabled, as required by federal law. What the one has to do with the other — and what either has to do with Mr. Perez's qualifications to run the Labor Department — is entirely unclear.

The controversy over the St. Paul case may get the most attention in the confirmation hearings. Republicans accuse Mr. Perez of negotiating a quid pro quo with St. Paul in an effort to preserve a key enforcement tool the Justice Department uses in housing discrimination cases, and that the Justice Department took a pass on the chance to recover millions in allegedly misused federal housing funds. A quid pro quo, if it existed, would certainly be unusual. But before jumping to conclusions about what happened, it is relevant to note that the Justice Department and St. Paul officials were not in disagreement about the principle at hand.

St. Paul had stepped up targeted enforcement of its housing codes in distressed neighborhoods in an effort to crack down on unsafe conditions, like rat infestations. Those sweeps often forced landlords to make expensive repairs, and the landlords sued, with a novel complaint. They said that the effect of the city's action was discriminatory because it could lead to a reduction in affordable housing in the city, which would disproportionately affect African-Americans and other minorities. In so doing, they relied on a long-standing tool the Justice Department has used in housing discrimination cases: the principle that an action need not be discriminatory in intent but merely in effect to be illegal. By the time the case was headed for the Supreme Court, civil rights groups, housing advocates, Walter Mondale and the Justice Department urged the city to drop the case for fear that the high court would use the occasion to overturn that principle, which was never the city's intent. Instead, it is now poised to fight the issue on its merits in federal district court.

What Republicans are really upset about in the nomination of Mr. Perez is that he worked hard to enforce voting rights laws at a time when GOP officials in states across the country were seeking to make it harder for people — particularly the poor and minorities — to register and vote. They don't like that as labor secretary in Maryland, he stood against predatory lending practices and in favor of enforcing fair pay laws. And many can't stomach his record of treating immigrants — legal or not — as human beings. Mr. Perez is energetic and smart, with clear eyes and a good heart. He's exactly the kind of person America's workers need looking out for them.